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W Burkart

Publications and source records attributed to W Burkart.

At least 19 recordsLinked to original sources
PubMed1999

A registry for exposure and population health in the Altai region affected by fallout from the Semipalatinsk nuclear test site.

A registry of the rural population in the Altai region exposed to fallout from nuclear tests at the Semipalatinsk test site (STS) was established more than four decades after the first Soviet nuclear explosion on August 29, 1949. Information about individuals living in an exposed and a control area was collected using all available local sources, such as kolkhoz documentation, school registries, medical treatment records and interviews with residents. As a result, a database comprising an exposed group of 39 179 individuals from 53 Altai region villages, 6769 external and 3303 internal controls was compiled. For several settlements, effective dose estimates reached the level of 1.5 Sv, while the average effective dose estimate in the exposed group was 340 mSv. Dosimetric data, vital status information and health records gathered at rayon and village medical facilities are held in the registry. Cause-of-death information for deceased residents is obtained from death registration forms archived at the Altai region vital statistics office. At present, a follow-up of approximately 40% of the population exposed in 1949 has been done. More will be added by searching for migrants to the larger towns of the Altai region, i.e. Barnaul, Rubtsovsk and Biisk. In order to assess the influence of radiation exposure, analytical studies with a case-control design for stomach and lung cancer are currently being prepared. The number of known cases is sufficient to detect an odds ratio of 1.5 at the 95% confidence level. Epidemiological studies in populations affected by fallout from STS may be equally important to the atomic bomb survivors' study for the direct quantification of radiation effects. The range of exposure rates experienced will extend the acute high-dose-rate findings from Hiroshima/Nagasaki towards acute and protracted lower exposures, which are more relevant for radiation protection issues.

Environmental Exposure↗
PubMed1999

Leukaemia in the vicinity of two tritium-releasing nuclear facilities: a comparison of the Kruemmel Site, Germany, and the Savannah River Site, South Carolina, USA.

In 1991, an increased rate of childhood leukaemia was reported from the small northern German community of Elbmarsch, which is located on the banks of the River Elbe opposite the Kruemmel nuclear power plant. Owing to the fact that the increase occurred six years after the start-up of the plant, radioactive discharges were suspected as being implicated in the development of the cases. Previous investigations have failed to identify any exposure which might be associated with the cluster. Nonetheless, concern regarding the increased tritium burden in the environment remains. To further assess the impact of tritium releases to the environment upon population cancer rates, the releases and leukaemia rates at the Savannah River site, USA, were compared with the Kruemmel site. Based on the data from 1991 to 1995, the incidence of childhood leukaemia in the vicinity of the Savannah River site was non-significantly less than expected compared with the significantly higher than expected rates close to the German plant. In contrast, tritium releases from the Savannah River site exceed those from the Kruemmel site by several orders of magnitude. The results of this observational study suggest that factors other than environmental tritium releases are associated with the increased number of leukaemia cases near the Kruemmel site.

Child↗
PubMed1999

The German uranium miners cohort study: feasibility and first results.

In Germany, the largest single cohort study on uranium miners to date is being conducted. The cohort includes about 64,000 workers of the former Wismut company in eastern Germany. Inclusion criteria were: a date of employment between 1946 and 1989, a minimum period of employment of 180 days, and complete information on working history. Due to poor working conditions in the late 1940s and early 1950s, miners were exposed to high levels of radiation, while later radiation exposure was significantly reduced. The aim of the cohort study is to evaluate the risk of lung cancer and other cancers associated with several indicators of exposure to radon and its progeny, with particular attention to low levels of radiation. Radon exposure will be estimated by a detailed job- exposure matrix. Some information about smoking, dust and arsenic is already available. About 49,000 miners are defined as exposed (underground or processing), while the internal control group (surface only) consists of 15,000 workers. A total of 1,436 lung cancer deaths among cohort members have been reported. The first mortality follow-up will be finished early in 2002, and a total of about 3,000 lung cancer deaths are expected by then.

Adult↗
PubMed1998

[Health risks of ionizing radiation].

Ionizing radiation from natural or man-made sources may affect human health. The main consequence of low and moderate radiation doses is the induction of cancer. To quantify these effects both epidemiological studies and experimental radiobiological research are needed. The ensuing results of the studies are used to establish radiation protection principles and dose limits to protect the public from the effects of ionizing radiation.

Environmental Exposure↗
PubMed1998

Direct beta measurements to determine in vivo whole-body activities of 90Sr in residents of the southern Urals: description of a new method.

For 44 individuals living in areas of the Southern Urals with historical 90Sr contamination, whole-body activities of this radionuclide were investigated using a new mobile detection system. Beta-particles from 90Sr/90Y decay were measured in vivo via two proportional counters mounted in front of the forehead and above the head, respectively. In order to correct for absorption by the skin, scalp thickness was measured using ultrasonic techniques. Corrections are given with respect to self-absorption by the bone matrix and absorption by hair. A procedure is described to extrapolate from measured 90Sr activity of the skull bone to total 90Sr skeleton burden. As a result, 90Sr whole-body activities of up to 50 kBq were recorded in the selected cohort. For the same individuals, 90Sr was measured via the detection of bremsstrahlung using an established whole-body counting device. The overall results of both systems agree within 15%, but differences exceeding a factor of 2 were observed in some cases.

Absorption↗
PubMed1998

Measurements of radioactivity in environmental samples from the southern Urals.

A region between Chelyabinsk and Ekaterinburg in the Southern Urals has been heavily contaminated due to operational and accidental releases from the first Soviet plutonium production facility Mayak. In 1992 and 1993, the German Federal Office for Radiation Protection organized a measuring campaign involving two Russian institutes to assist with the validation of former Soviet measurement data. The results of this measuring campaign are reported here. Environmental samples were collected from areas affected by significant radioactive releases into the Techa river, which started in 1948, and by fallout from the explosion of a fission product storage tank in 1957. Soil, sediment, water, milk and food samples were independently analysed for 90Sr, 137Cs and plutonium by the three institutes involved. This paper presents data on the present levels of environmental radioactivity. The highest contamination of areas accessible to the local population was found in the vicinity of the Techa river around Muslumovo. Activity concentration of floodplain samples reached up to 37,000 Bq.kg-1 137Cs, 5,600 Bq.kg-1 90Sr and 9.9 Bq.kg-1 Pu. Milk and potatoes from private farms in Muslumovo showed low activity in the range from 0.7 Bq.kg-1 to 25 Bq.kg-1 90Sr. The results of the three independent measurement teams showed sufficient agreement. One Russian laboratory obtained plutonium activities that exceeded the results of the other laboratories by about 20%. Contrary to the International Chernobyl Project, there was no overestimation of 90Sr activities in the Russian analyses. Therefore, the validity of earlier data sets acquired with same methodology and quality control can be considered a valuable basis for further assessments and for dose reconstruction in epidemiological projects.

Animals↗
PubMed1998

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Germany↗
PubMed1998

Trends in infant leukaemia in West Germany in relation to in utero exposure due to Chernobyl accident.

A temporary increase in the incidence of infant leukaemia in Greece was reported by Petridou et al., which was attributed to in utero exposure to ionising radiation resulting from the Chernobyl accident. We performed a similar analysis based on the data of the German Childhood Cancer Registry in order to check whether the observation could be confirmed by means of independent data. Applying the same definitions as Petridou et al., we also observed an increased incidence of infant leukaemia in a cohort of children born after the Chernobyl accident. More detailed analyses, regarding areas with different contamination levels and dose rate gradients over time after the accident, showed, however, no clear trend with regard to exposure. It would therefore appear less likely that the observed effect was caused by exposure to ionising radiation due to the Chernobyl accident.

Child, Preschool↗
PubMed1998

Health risks from combined exposures: mechanistic considerations on deviations from additivity.

Living organisms are exposed every day to a multitude of physical, chemical and biological agents. However, assessments of possible deleterious outcomes from these exposures concentrate on single agents and neglect the potential for combined effects, i.e., synergisms or antagonisms. Biomechanistic considerations based on multistep processes such as carcinogenesis indicate the potential for highly detrimental interactions, if two or more consecutive rate limiting steps are specifically effected by different agents. However, this depends on the specificity of the individual agents for well defined molecular structures or DNA sequences. Low specificity towards molecular structure or DNA-sequence-and therefore exchangeability-of many genotoxic agents indicate little functional specificity of most agents and therefore little vulnerability towards synergism at most occupational and non-occupational exposure situations. In addition, the relative insignificance of combined actions for those common exposure situations where highly non-linear dose effect relationships for non-genotoxic acting agents are involved is also evident. However, an experimental proof of the quantitative assessment of the contribution of synergistic interactions to the total detriment from natural and man-made toxicants is remote. Surprises therefore cannot be excluded.

Carcinogens, Environmental↗
PubMed1997

Quantifying health effects from the combined action of low-level radiation and other environmental agents: can new approaches solve the enigma?

Efforts to assess the quantify deleterious effects from toxicants are directed mainly towards single agents, whereas real world environmental and occupational exposures to natural and anthropogenic agents quite often entail the concomitant presence of several toxicants. These combined exposures may lead to health risks that differ from those expected from simple addition of the individual risks. For example, combined exposures to physical and chemical agents such as radon and smoking or asbestos and smoking produce over-additive effects at exposure levels typical for earlier workplaces. In tumour therapy, the modulation of radiation effects by cytotoxic drugs is widely used to enhance the therapeutic gain. Whether interactions occurring at high exposure levels are important at the low exposure levels set for the public and for modern workplaces is difficult to answer. A scientifically sound extrapolation from these high to low-dose levels should be based on dose-effect relationships of the relevant agents alone and in combination. In general this information is not available. The existing data base on combined effects is rudimentary, mainly descriptive and rarely covers exposure ranges large enough to make direct inferences to present day low-dose exposure situations. In view of the multitude of possible interactions between the large number of potentially harmful agents in the human environment, descriptive approaches will have to be supplemented by the use of mechanistic models for critical health endpoints such as cancer. To generalise and predict the outcome of combined exposures, agents will have to be grouped depending on their physical or chemical mode of action on the molecular and cellular level. Such a grouping must be guided by specific mechanistic studies designed to examine the underlying hypothesis regarding how various classes of agents interact.

Animals↗
PubMed1997

Down syndrome clusters in Germany after the Chernobyl accident.

In two independent studies using different approaches and covering West Berlin and Bavaria, respectively, highly significant temporal clusters of Down syndrome were found. Both sharp increases occurred in areas receiving relatively low Chernobyl fallout and concomitant radiation exposures. Only for the Berlin cluster was fallout present at the time of the affected meioses, whereas the Nuremberg cluster preceded the radioactive contamination by 1 month. Hypotheses on possible causal relationships are compared. Radiation from the Chernobyl accident is an unlikely factor, because the associated cumulative dose was so low in comparison with natural background. Microdosimetric considerations would indicate that fewer than 1 in 200 oocyte nuclei would have experienced an ionizing event from Chernobyl radioactivity. Given the lack of understanding of what causes Down syndrome, other than factors associated with increased maternal age, additional research into environmental and infectious risk factors is warranted.

Down Syndrome↗
PubMed1997

Enhanced neoplastic transformation in an inhomogeneous radiation field: an effect of the presence of heavily damaged cells.

In the inhomogeneous radiation field surrounding small beta-particle sources, nonlethally and heavily damaged cells are in proximity, permitting interaction via extracellular signals. This situation is typical of hot particles such as those released during the accident at Chernobyl. Beta-particle-emitting yttrium-90 wires (average energy 934 keV) were employed to investigate radiation-induced neoplastic transformation under these conditions. Integrated 24-h doses ranging from 0 to 750 Gy across the exposure field were applied. At equal levels of toxicity a 10-fold enhancement of neoplastic transformation frequency in C3H 10T1/2 cells was observed in the presence of heavily damaged cells. Homogeneous fields of low-dose-rate beta-particle radiation produced neoplastic transformation frequencies typical for comparable photon exposures reported in the literature.

Animals↗
PubMed1996

Human cytogenetic consequences of the Chernobyl accident.

The frequency of chromosomal aberrations was evaluated in more than 500 liquidators of the Chernobyl accident. The 'sarcophagus' builders and the dosimetrists showed the highest frequency of aberrations per 100 cells: 3.24 +/- 0.25 and 3.11 +/- 0.43. For Chernobyl Atomic Power Station staff members the mean frequencies of aberrations per 100 cells was 2.37 +/- 0.20. The mean yields of aberrations in the other groups was between 1.31 and 1.47 per 100 cells. If the mean frequencies of aberrations are converted into equivalent whole body doses, values between 136 and 414 mGy are obtained. Especially in the group of 'sarcophagus' builders, the yields of aberrations varied interindividually and corresponded to equivalent whole body doses of up to about 2 Gy.

Chromosome Aberrations↗
PubMed1996

Radioepidemiology in the aftermath of the nuclear program of the former Soviet Union: unique lessons to be learnt.

The military and civilian nuclear activities in the former Soviet Union led to unique exposures and resulted in high cumulative doses in several populations. In comparison to the atomic bomb survivors, at present the most important cohort in radiation epidemiology, collective and individual doses received by early workers in the plutonium production facilities at Mayak (Chelyabinsk). Techa River residents downstream of Mayak, populations downwind of the Semipalatinsk test site, and subpopulations of Chernobyl victims surpass the Hiroshima/Nagasaki experience in most cases. Even more importantly, the dose rates cover the full range of exposures relevant for radiation protection. i.e., acute to year-long chronic exposures from environmental contamination and bone seeking radionuclides. Parallel to the humanitarian need to mitigate health effects from these exposures, the unique opportunities for research on radiation risks related to low dose rate and chronic radiation have to be explored. Increased efforts by the global radiation research community are needed to address the many questions which cannot be answered by the acutely irradiated survivors of Hiroshima/Nagasaki. Specific attention needs to be drawn to the validation of available exposure and health records and to dose reconstruction which must include dietary sources of exposure. Preliminary intercomparison and validation exercises indicate potentially large sources of error, e.g., due to uncertainties in the reconstruction of early exposures and effects and due to continuing incorporation.

Dose-Response Relationship, Radiation↗